Recently there are more and more vehicles using the multi-link system (double wishbone system) because they control the vehicles alignment changes more actively. Most of these vehicles have a rubber bush at the point installing in the suspension arm. Here we will look at the influence of the rubber bush.

We will look at the front end of the MAZDA RX-8 as our example. When changing the front shock absorber on the RX-8, first you need to remove the upper arm (Photo 1) from the body. Usually you will use a jack or lift to perform the installation process of the shock absorber, but afterwards, do not tighten the bolt of the upper arm, with the car jacked up/ lifted up. If you do tighten the upper arm bolt with the car jacked/ lifted up (Photo 2) there have been some situations when the ride height does not drop on the vehicle on level/ flat ground (1G state). This is because the rubber bush, between the vehicle body and the upper arm, becomes twisted and restricts the vehicle ride height from dropping. In a worst case scenario, the rubber bush may become damaged, so please take care.

To avoid this from happening, only permanently tighten the upper arm bolt when the vehicle is jacked/ lifted up. When the car is on level ground (1G state), permanently tighten the bolt. (Photo 3) Doing this will prevent the rubber bush from becoming twisted and will not interfere with the vehicles ride height. This problem is not just for the MAZDA RX-8, but mainly for vehicles with multi-link and double wishbone suspensions. When installing shock absorbers or low-down springs on these types of vehicles, you need to tighten the arm bolt with the vehicle at 1G. For arms that use pillow balls, such as the rear setup on the LANCER EVO. 7 - 9, it is not limited to this problem.

Also a similar problem occurs after installing shock absorbers or low-down springs on vehicle is at 1G if the hand brake is not released (HONDA FIT GD2/4). These kind of problems may occur, so please tighten the arm bolt with the vehicle at 1G, then take a test drive and recheck the measurements.